MORRISVILLE, N.C.--(BUSINESS WIRE)--Oxygen Biotherapeutics, Inc., (NASDAQ: OXBT) a developer of oxygen-carrying therapeutics, today announced the Company has converted $4.6 million in outstanding principal amount of a convertible promissory note. The note, which was scheduled to mature on July 1, 2014, carried an interest rate of 15% per annum. This move reduces the Company’s debt from $4.9 million to $300,000. The Company estimates that this will improve its net shareholder equity by approximately $3.5 million.